How much do your Cummins VT-903’s smoke when cold?

[sgharford]

I think the engines smoke less then when I bought her 3 years ago. Previous owner only put 60 hours on engines in 5 years (By chance my engine surveyor did the survey for prev owner when he bought boat). I actually did install block heaters this year - no easy task on a 903. I have to finish up my thread on that later this month. Have yet to really kick tires on block heaters.

I'm not overly worried about the smoke, outside of pissing other people on dock off, which I don't lose any sleep over. Was excited to finally find proper tools to do injector and valve timing this winter after 3 years on the hunt. I hate doing projects during the boating season, that's what winter is for, so I will wait for end of season on this one (want her in water so I can test when I'm done).

Point of this thread was to establish base line of what is normal for old 903 in terms of smok'n. Got a good PM on subject along with your guys feedback all seems normal as I described. Thanks all.

[34Hatt]

I got the same general response about tank maintenance when I asked the question 2 years ago and picked up a couple of quarts of AJX. Curious about AJX boosting Cetane rating, guess it does. I know I still had enough smoke to make my neighbors run below every time I cranked em over when I was using it (sail boaters mind you). Unless it's your gas making the stank, it's hard to enjoy it

Yes it does raise your cetane

[jim rosenthal]

See what they do once you get the block heaters up and running. Most engines smoke far less at startup when they are preheated with pan or block heaters. The problem may go away by itself. I think white smoke is unburnt fuel, isn't it? My guess is that once the heads are warmed up the fuel burn pattern is much more even and more effective.

[REBrueckner]

"...I think the engines smoke less then when I bought her 3 years ago. Previous owner only put 60 hours on engines in 5 years..."

No surprise. With block heaters, I'd not even give it a second thought...

"I hate doing projects during the boating season, that's what winter is for.."

Amen.....


Other discussions here on Sam's properly note than an engine with hardly any running time builds up some corrosion in the cylinder walls as a result of the moist marine environment...and so when the engines are finally run with some regularity, the pistons (hopefully) scrape the cylinder walls clean and combustion/compression actually improves t....Hence if an oil analysis is done on an engine that has been sitting around iron content, for example, may show a lot higher than after a season of regular use...